The present invention relates to an apparatus for driving a medical appliance such as an artificial heart or balloon pump in the artery, and more particularly to a fluid driving apparatus for changing a positive fluid pressure and a negative fluid pressure.
The conventional driving apparatus for a medical appliance is shown in, for example, Japanese Patent Laid-Open Application No. 61(1986)-12900. In this conventional apparatus, the apparatus has one compressor for producing both positive and negative pressures. An outlet terminal of the compressor is connected to a one-way valve and a switching valve and an inlet terminal of the compressor is also connected to a one-way valve and a switching valve. When it is in a positive pressure applying period, positive pressure regulation has priority. On the other hand, when it is in a negative pressure applying period, negative pressure regulation has priority. If both a positive and a negative pressure are above each setting pressure, respectively, both switching valves are opened. Thus the compressor is idle, because the compressor draws air from the atmosphere and exhausts air to the atmosphere. Then this apparatus can generate both positive and negative pressures by a single compressor.
However, this apparatus makes undesirable noise because the compressor is often operated in the idle mode. Furthermore, when the compressor operates in the idle mode, power consumption may increase.